The architecture of carbon fiber-TiO2 nanorods hybrid structure in supercritical water for reinforcing interfacial and impact properties of CF/epoxy composites

To improve the interfacial properties of carbon fiber (CF)/epoxy composites, the growth of titanium dioxide nanorods (TiO2 NRs) on CF surface was obtained by hydrothermal and supercritical methods. The microstructures, morphologies and mechanical properties of CF-TiO2 NRs before and after architecture were investigated, which indicated that TiO2 NRs were grown uniformly onto CFs. The polarity, roughness and wettability of CF-TiO2 NRs were increased distinctly in comparison with those of untreated CF, especially in supercritical water, indicating that supercritical water has ameliorated the growth efficiency and promoted the TiO2 NRs onto the CF surface more compactly. The interfacial shear strength (IFSS) and impact strength of composite could be increased as high as 50.7% and 50.0% without deteriorating fiber tensile strength in supercritical water. Meanwhile, the interfacial reinforcing and toughing mechanisms of hybrid fiber composite have also been elaborated. It is believed that the effective method would offer a novel interface design ideology for developing high performance composites.